Conventionally, there has been proposed or suggested that copper or copper alloy element wire is substituted by aluminum or aluminum alloy element wire in the conductor portion of an electrical wire so as to decrease the weight of wiring harness to be disposed in a vehicle. For example, see Japanese Publication of Patent Application No. 2009-170315A. The electrical wire to which a terminal fitting is coupled or attached can be mounted to the wiring harness.
However, aluminum or aluminum alloy material generally has less mechanical strength in comparison with copper or copper alloy material which has been used as element wire material for a conductor of an electrical wire. Accordingly, in a case where an electrical wire having a conductor portion composed of aluminum or aluminum alloy element wire(s) is employed in a wiring harness for a vehicle, in particular, the door portion of vehicle, the element wire is prone to break or fracture.